Lip sync is only an issue if you're doing video processing with the TV (like upconverting or stretching). The TV's processor doesn't have the oomph to mangle the video in real time so it falls out of sync with the audio (which it isn't mangling). The simple solution is to turn off any "extra" processing of the video and have the source do the processing (upconverting DVD or upconversion on the cable box).

If you don't already have a TV with this problem and are worried about a new set, I suspect it won't be an issue with anything of recent (2005+) vintage.